“It’s a question we can’t answer for sure. Lots of people have been telling me about creatine and it does make you wonder.

“I would be happy if somebody came through with a study to help with that – and to help the young people who are taking it now.

“We need to know what are the side effects of taking it. I would love to know that because we can advise the young people about the right way to go.”

The duo first started playing together for Counties Manukau in 1994, and then for the all-conquering Auckland Blues from 1996.

They were coached by Sir Graham Henry – who later led the All Blacks to their second World Cup triumph, in 2011 – and included stellar names such as skipper Sean Fitzpatrick, Zinzan Brooke and Olo Brown.

As well as being the dominant side in New Zealand, the Blues won the Super 12 competition in 1996 and 1997.

Vidiri, who was diagnosed with nephrotic syndrome in October 2001, remembers: “We used to be given a really big container of it [creatine] every few months.

“Instructions were written on the back and we would take the container away with us.

“We used to mix it with water and it would puff you up. I can’t remember how much we would take anymore. We took it before we trained and after too.

"Jonah would take it too, though maybe not as much, because he was already on the drugs for his kidney condition," he said. We took it from 1997 onwards. We used to have a corner in the dressing room where we'd sit together.

“We were good mates. When you’re young, you're so desperate to be up there, to get anything that can help you move forward with your rugby career. There was a lot of pressure on us, because we had to perform. We’d just started to be paid, it was semi-professional. We had to perform week in, week out.

Unstoppable: Jonah Lomu had it all and he was unplayable at times

“For the Blues, you had to perform to be in the starting line-up the next week. The supplements were part of that because you wanted to get stronger. The game was getting tougher and faster. You wanted something to help you improve in your rugby career.

“I stopped taking creatine when we started to get worried about what it was doing to us. As soon as there were rumours about it, I stopped.”

Lomu training for the All Blacks

Dr John Mayhew, who was Lomu’s personal GP as well as being the All Blacks’ doctor, denies that the legendary wing took creatine.

“Jonah never took creatine,” he told Telegraph Sport.

“We knew he had a renal impairment for most of his career, so he definitely wasn’t taking it. It is not a banned substance, but as a rule of thumb I advise anyone with kidney problems not to take it.”

“I don’t know what dietary advice he was given, but with Lomu heading towards dialysis, he should have been given advice not to take it,” he said.

“There is no evidence that creatine hampers kidney function in a healthy patient. However, it could accelerate the loss of nephrons – the units that filter blood - in someone with a pre-existing condition.

Kalra said there is evidence that “massive people are more predisposed to nephrotic syndrome” and research has shown that Polynesians have a higher predisposition towards the condition than average.

Fitzpatrick, who captained Lomu and Vidiri for both the Blues and All Blacks, admits members of his Auckland side routinely took creatine, but insists its use was closely regulated.

Former England scrum-half Kyran Bracken says players used creatine during the 2003 World Cup

“We had sports science and trainers at the time,” he said. “It’s all about the way you use creatine. It wasn’t simply a case of being given a container and getting told: ‘Go take it.’

“There was supervision, there was advice, and not everyone was on it. I certainly wasn’t a big user of it myself.”

Creatine has been a popular dietary supplement for rugby players for more than 20 years.

Former England scrum-half Kyran Bracken says players used it both in the run-up to, and during, the World Cup-winning campaign in 2003.

“Some of the players who wanted to get bigger certainly used creatine,” Bracken told Telegraph Sport.

“I have no idea whether it’s good or not to be honest. For me, it was more important to be light and fast and I didn’t want to build up too much muscle, so I didn’t use it. But a lot of the lads did, definitely."

Nutritionist Fred Wadsworth, who worked with England under Sir Clive Woodward, said any professional player who fails to use creatine is “missing a trick”.

“Any forward would be mad not to take it because of the benefits in terms of bulk and power,” he said.

“It is legal and has been widely used in rugby for two decades, without any problems. If you have underlying renal issues then it’s not a good idea to take it though."